Sunday, July 24, 2011

A Ruthless Killer of its Own Kind


Inhabiting a wide variety of places on Earth; including but not limited to the soil, water, plants, animals, and even humans, Pseudomonas aeruginosa is known to many as the culprit which causes physical aliments such as pneumonia, urinary tract infections, and bacteremia (an invasion of the bloodstream by bacteria- http://medical-dictionary.thefreedictionary.com/bacteremia). Even though it’s usually not dangerous to individuals with healthy immune systems this bacterium strikes those who aren’t as healthy. Even more interesting, this bacterium is “the most common pathogen isolated from patients who have been hospitalized longer than one week” - http://emedicine.medscape.com/article/226748-overview. However, could this less than favorable bacterium be used for the good of all men, and if so, how could it?

In a recent study conducted at the University of Washington by Alistair Russell, Mr. Russell has found that these bacteria do something truly marvelous, they “inject toxins into rival bacteria with a needle-like puncturing device…[which] degrade competitors’ protective barricades—their cell wall” “By killing off its competitors, P. aeruginosa widens its territory, leading to its overall success,” say Russell. As Mr. Russell goes on to explain, these bacteria inhabit places where other types of bacteria take residence. They, like all living organisms, must find a way to survive in the environments they live in, which just happens to be by piercing other bacteria’s defense mechanisms, their cell wall. How exactly do they do this; break down the cell wall of an opposing bacterium to eradicate them? Russell has pinpointed down the exact mechanism that does this, the type VI secretion system, or the T6SS. This device, “transports toxins so that they never enter P. aeruginosa’s cell wall space… [this then] delivers toxic proteins that degrade the cell wall. After the cell wall is compromised, the cell bursts like an overfilled water balloon.” It’s interesting to have found that this type of bacterium does this. As Russell mentions, its actions of injecting and killing other bacteria are similar to those of viruses, or bacteriophages. To answer my question above, this bacterium, rather, this bacterium’s system, the T6SS, could prove to be useful to the common man. Russell did not overlook this possibility either, "We might be able to take helpful bacteria, give them this system genetically, and increase their ability to clear out professional pathogens -- those bacteria that make their living causing disease." However, this does draw another point, how would we do this? Again, Mr. Russell has thought about this question as well. “One limitation is that bacteriophages are relatively unstable and require a host bacterium to increase their numbers.” Even though there are limitations such as this one, this could ultimately mean that in the near future scientist and drug companies could collaborate together and create a new type of antibiotic drug in which could act like P. aeruginosa and attack invading bacteria. Until then, Mr. Russell, his colleagues, and others who wish to probe the potential positive effects of engineering new drugs with this capability will without a doubt have to go through more research and testing to become even closer to finding a way.

Sources:

http://www.sciencedaily.com/releases/2011/07/110720142129.htm

http://emedicine.medscape.com/article/226748-overview

http://medical-dictionary.thefreedictionary.com/bacteremia

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